diff --git a/functions.c b/functions.c
index 37252d7..5efd088 100644
--- a/functions.c
+++ b/functions.c
@@ -5,6 +5,7 @@
 
 #include "lang.h"
 #include "main.h"
+#include "util.h"
 
 void lenv_add_builtin(lenv* env, char* sym, lbuiltin func) {
     lval* symval = lval_sym(sym);
@@ -392,10 +393,38 @@ lval* builtin_lambda(lenv* env, lval* val) {
     return lambda;
 }
 lval* builtin_load(lenv* env, lval* val) {
-    LASSERT_ARG_COUNT("load", val, val, 1);
+    LASSERT_MIN_ARG_COUNT("load", val, val, 1);
     LASSERT_TYPE("load", val, val->cell_list[0], LVAL_STR);
     
-    char* filename = val->cell_list[0]->data.str;
+    lval* fileval = NULL;
+    lval* option = NULL;
+    
+    if (val->cell_count == 1) {
+        fileval = val->cell_list[0];
+    } else if (val->cell_count > 1) {
+        LASSERT_TYPE("load", val, val->cell_list[1], LVAL_STR);
+        option = val->cell_list[0];
+        fileval = val->cell_list[1];
+    }
+    
+    lenv* rootenv = lenv_get_root(env);
+    
+    char* filename = fileval->data.str;
+    
+    BOOL file_loaded = FALSE;
+    for(int i =0 ; i < rootenv->loaded_files_count; i++) {
+        if (strcmp(filename, rootenv->loaded_files[i]) == 0) {
+            file_loaded = TRUE;
+            break;
+        }
+    }
+    
+    if (option != NULL && strcmp(option->data.str, "once") == 0) {
+        if (file_loaded == TRUE) {
+            lval_delete(val);
+            return lval_s_expr();
+        }
+    }
     
     mpc_result_t result;
     if (mpc_parse_contents(filename, gLispy, &result)) {
@@ -412,19 +441,21 @@ lval* builtin_load(lenv* env, lval* val) {
             lval_delete(x);
         }
         
+        if (file_loaded == FALSE) {
+            rootenv->loaded_files = realloc(rootenv->loaded_files, sizeof(char*) * rootenv->loaded_files_count+1);
+            rootenv->loaded_files[rootenv->loaded_files_count] = strdup(filename);
+            rootenv->loaded_files_count++;
+        }
+        
         lval_delete(resultLval);
         lval_delete(val);
-        
+                
         return lval_s_expr();
     } else {
         //Parse error
         char* errorMessage = mpc_err_string(result.error);
         mpc_err_delete(result.error);
         
-        char cwd[1024];
-        getcwd(cwd, sizeof(cwd)-1);
-        printf("dir: %s\n", cwd);
-        
         lval* err = lval_err_detail(LERR_OTHER,"Load: %s", errorMessage);
         free(errorMessage);
         lval_delete(val);
diff --git a/lenv.c b/lenv.c
index 73c0af2..6e25ded 100644
--- a/lenv.c
+++ b/lenv.c
@@ -8,15 +8,24 @@ lenv* lenv_new() {
     env->count = 0;
     env->parent = NULL;
     env->syms = NULL;
+    env->loaded_files_count = 0;
+    env->loaded_files = NULL;
     return env;
 }
 void lenv_delete(lenv* env) {
     for(int i = 0; i < env->count; i++) {
-        lval_delete(env->syms[i]->lval);
-        free(env->syms[i]->sym);
-        free(env->syms[i]);
+        symtab_delete(env->syms[i]);
     }
-    free(env->syms);
+    for(int i = 0; i < env->loaded_files_count; i++) {
+        free(env->loaded_files[i]);
+    }
+    if (env->loaded_files_count > 0) {
+        free(env->loaded_files);
+    }
+    if (env->syms != NULL) {
+        free(env->syms);
+    }
+    env->parent = NULL;
     free(env);
 }
 lenv* lenv_copy(lenv* env) {
@@ -59,6 +68,13 @@ symtab* lenv_search(lenv* env, char* sym) {
     }
     return *result;
 }
+lenv* lenv_get_root(lenv* env) {
+    if (env->parent == NULL) {
+        return env;
+    } else {
+        return lenv_get_root(env->parent);
+    }
+}
 
 lval* lenv_get(lenv* env, lval* sym) {
     LASSERT(sym, sym->type == LVAL_SYM, LERR_BAD_OP, "Expected symbol");
diff --git a/lenv.h b/lenv.h
index 2b91cc5..b1624bc 100644
--- a/lenv.h
+++ b/lenv.h
@@ -26,6 +26,8 @@ extern "C" {
     struct lenv {
         size_t count;
         struct lenv* parent;
+        char** loaded_files;
+        size_t loaded_files_count;
         struct symtab** syms;
     };
 
@@ -36,6 +38,7 @@ extern "C" {
     int lenv_compare_symtabs(const void *a, const void *b);
     void lenv_sort(lenv* env);
     symtab* lenv_search(lenv* env, char* sym);
+    lenv* lenv_get_root(lenv* env);
     
     lval* lenv_get(lenv* env, lval* sym);
     void lenv_put(lenv* env, lval* key, lval* val);